The mechanism of ovulation is a complex process involving a number of morphological and biochemical changes, including protein and RNA synthesis, steroidogenesis, cyclic AMP synthesis, prostaglandin synthesis and probably an increase in enzyme activity leading to weakening of the wall of the mature follicle. The actual rupture of the follicle may also involve muscle contractions and changes in the microvasculature of the follicle. Luteinizing hormone sets the ovulatory process in motion, but the exact mechanism involved is as yet unknown. We have developed a hypothetical biochemical model of ovulation which attempts to put together some of the existing data with some recent results from our laboratory on changes in steroidogenesis, cyclic AMP synthesis, and prostaglandin synthesis in the Graafian follicle during this process. The purpose of the model is to point out crucial aspects which can be tested. The main thrust of our experimental approach is to study the role of prostaglandins in ovulation. We have previously shown that prostaglandins E and F, increase immediately prior to ovulation in rabbit Graafian follicle, and we plan to study how this increase is brought about and what the role of this increase is in regards to the follicular rupture. All our studies will be carried out using either rabbit Graafian follicles or follicles obtained from PMSG-treated immature rats. We will explore in detail the interactions between luteinizing hormone, cyclic AMP, steroidogenesis, protein and RNA synthesis, prostaglandin synthesis and the synthesis or activation of the ovulatory enzyme.